Secret agents will be used to infiltrate gangs involved in smuggling illegal immigrants into Europe under a plan to clamp down on criminals who are making billion-dollar profits while showing scant regard for the safety of their human cargo.

European governments have pledged to step up co-operation to catch those responsible for the illegal trade and agreed to tighten laws to make sure those behind the gangs can be brought to justice.

The International Organisation for Migration has estimated that global immigration racketeering is worth about US$7 billion (HK$54.5 billion) a year, with many of the migrants being smuggled into Europe. Immigration authorities say there are at least 50 criminal gangs involved in smuggling people, with different syndicates concentrating on different parts of the world.

A United Nations High Commission for Refugees report suggests as many as 200,000 people each year are smuggled into the European Union, with most heading for Germany or the UK.

But following the tragic deaths this week of 58 Chinese migrants who died of suffocation in the back of a truck after being smuggled into the British port of Dover, authorities across the continent have agreed to tighten up regulations to apprehend the criminals responsible.

The issue was raised at a meeting of European Union heads of government in Lisbon earlier this week, where British Prime Minister Tony Blair urged leaders to renew their efforts to crack down on the syndicates responsible.

Ministers from the 15-member nations have agreed to standardise regulations to ensure the pursuit and conviction of gang leaders is made easier. The British National Crime Squad confirmed that agents from the country's secret service would be used to infiltrate gangs responsible for trafficking in illegal immigrants.

Agents from Britain's MI5, responsible for counter-terrorism within the UK, would be deployed to try to penetrate gangs working within Britain, while agents from MI6, involved in espionage overseas, would be used to get close to gangs in countries where the migrants came from.

The National Crime Squad's director-general, Ray Penrose, recently held meetings with police chiefs from other European countries to co-ordinate a joint effort to crack down on those involved.

"The tragic incident at Dover further concentrates all our minds on the danger and misery caused by those who traffic in people for profit," Mr Penrose said. "Behind these events are some very evil and ruthless people who often smuggle other commodities too, including drugs, and are actively involved in international organised crime."

But experts say many migrants are resorting to illegal immigration because European countries have tightened visa regulations.

"The main reason illegal immigration appears to be growing is that restrictive immigration policies have increased, making it difficult for people to arrive in Europe legally," Dr Khalid Koser, from London University's Migration Research Centre, said. "There is no doubt that these criminal gangs are now going out and marketing themselves, telling people they will be able to get them into Europe and because it is more difficult to get visas they are able to charge higher fees."

Most European governments were more interested in stopping the arrival of new migrants than in catching the masterminds behind the illegal trade, he said.

"Clearly, governments are motivated by stopping the arrival of asylum-seekers. The big danger if they crack down on illegal immigrants is that they will also close down the routes used by genuine refugees to flee from persecution," Dr Koser said.

But while European governments were trying to stop the arrival of new migrants, falling birth rates suggest it might soon have to begin lowering immigration barriers to attract foreign workers.

"Europe's population is falling. If you take Italy as an example, the Italian population is estimated to fall by 28 per cent by the middle of this century," Ben Hall, research director at the Centre for European Reforms said. "I think it is realistic that the European Union will move to a situation where we will have annual quotas for the number of immigrants to come into Europe."

The European Union laws which allowed the free movement of people across the borders of all 15-member nations mean the quotas would have to be agreed by all governments. Britain and Germany are already examining this issue as they attempt to recruit information technology workers from India and Eastern Europe.